Can and facilities for its production, filling, and sealed closure

ABSTRACT

A can formed from an unfolded foldable cylinder having at least two folding edges. The folding edges are formed and arranged such that the foldable cylinder can be flattened for transport prior to the insertion of a closure member. The foldable cylinder is preferably unfolded and tightly sealed with at least one closure member at a first cylinder end region immediately before filling. By connecting the closure member to the foldable cylinder, the cylinder is given a desired shape or cross-section, at least in the region of the closure member. After the cylinder is filled, a further closure member is sealed to a second cylinder end region to seal the can and to impart the desired shape to the cylinder in the second end region, too.

BACKGROUND OF THE INVENTION

[0001] The invention relates to cans, i.e., sealed canisters, and the production and use thereof.

[0002] In general, cans as referred to herein differ from boxes or cartons in that cans are hermetically sealed, i.e., the contents are sealed in liquid-tight and preferably gas-tight fashion. Boxes or cartons, on the other hand, are typically closed simply by means of tabs or flaps or folded-in corner portions that do not provide for such tight, hermetic sealing.

[0003] In boxes—in particular, boxes having a lateral or body portion formed at least partly from cardboard or, if desired, plastic—the box is often provided at the box factory with at least one closure element that extends transversely to the box axis. In the case of “combination boxes,” for example, a removable aluminum closure member is inserted into the open body portion of the box in such a way that a plastic lid can be inserted from the open end of the body portion up to the membrane. Lids or outlet devices which permit the bulk material or liquid to be withdrawn from the box are often used as the closure member. Such boxes are generally transported, with open bottoms, to a filling company or station where the bottom is inserted into the body portion after filling. The empty boxes are transported occupying the same volume as in the filled state.

[0004] The field of boxes reveals foldable box preforms which are collapsed for transportation from the production site to the site where they are filled. The preforms are essentially flat and therefore require substantially less space than in the uncollapsed state.

[0005] EP 0 241 026 A2, for example, discloses a foldable, cylindrical box or carton that is formed from a cardboard “blank.” The blank, or cardboard sheet, is in one piece and comprises a portion that forms the lateral surface of the box and portions that form rosette closure surfaces connected to one another, at opposite sides of the lateral surface-forming portion, via folds and connecting surfaces. In order to yield a circular cross-section when the box is formed, the rosette closure surfaces are bounded by the lateral surface-forming section by arcuate flutes. The rosette closure surfaces are not suitable for tightly sealing the container or for ensuring easy opening and closing. In addition, the blank is transported in open, completely flat form and must be shaped into a cylinder at the filling site by gluing together end regions of the lateral surface section. Exact and tight connection of the two end regions of the lateral surface section is complicated and cannot be guaranteed at the filling site.

[0006] Even when the packaging containers have closure members, i.e., bottoms or lids, that are connected to the lateral surface by means of a plurality of flaps arranged around the perimeter of the closure member, it is difficult to obtain tight seals because it is not always possible to avoid small gaps or passages between the flaps. Therefore, in order to protect the contents of such poorly sealable packaging containers from external influences, said containers are used merely as stabilizing containers for holding tightly sealable bags, as shown, for example, in U.S. Pat. No. 3,204,849.

[0007] A further disadvantage when such sheets are connected together in an annular manner (regardless of whether they are glued to form a cylinder at the filling site or at the container production site) is that each sheet must be fed individually to a folding station and then to a gluing station in order for the sides opposite one another to be connected to each other along an overlapping region. The packaging element has twice the wall thickness in the overlapping region, making it more difficult to seal the packaging element tightly with the closure members.

[0008] Therefore, in order to form “closed” (i.e., continuous or non-interrupted) lateral surfaces with a constant wall thickness, cardboard webs often are wound around a stationary mandrel, the resulting cardboard tube then being pulled away from the mandrel along the mandrel axis and cut into sections. The cardboard webs are generally wound at oblique angles relative to the mandrel axis. The surfaces of the cardboard webs which are adjacent and contact each other must be glued together under tension. This gives rise to extremely complex friction problems as a result of the axial movement of the resulting tube over the mandrel, particularly as a result of the gluing-related tension in the cardboard webs, and the use of lubricants is not practical because it is important not to soil the inner lateral surface, which contacts the product packaged in the container.

SUMMARY OF THE INVENTION

[0009] It is an object of the invention to provide a can which can be transported and stored in a compact manner and which can be provided as a fillable can that is hermetically sealed at a filling site at low cost.

[0010] The can is formed by unfolding a folded cylinder having at least two folding edges, the folding edges being formed (in particular bent and/or fluted) and circumferentially located in such a way that the lateral wall or body-forming portion of the can can be collapsed flat before insertion of a closure member. In the flat state, the volume of the cylindrical, body-forming member corresponds essentially to the material volume. In other words, essentially no empty volume is transported during transportation from the cylinder factory to the filling line. The foldable cylinder is unfolded—preferably just before filling—and is sealed with at least one closure member at a first end thereof. By connecting the foldable cylinder to the closure member, the cylinder is given the desired shape cross-section, at least in the region of the closure element. After the can is filled, a further closure member may be sealed to the opposite end of the lateral surface or body member so that the can is completely sealed and the cylinder has a desired shape at the second end as well.

[0011] The second closure member does not necessarily have the same shape as the first one. For example, to achieve a particular design effect, one closure member may be circular and the other oval or hexagonal.

[0012] It is also possible to dispense completely with the second closure member by pressing the open end of the can together and welding it shut along a line if the inner surface is coated (at least in this region) with a hot-melt adhesive. This yields an upright “pocket” configuration. It is of course possible to fold this heat-seal seam over or to cover it with an overlapping strip.

[0013] In a folding can according to the invention, the closure members are initially completely separate from the lateral surface portion. The closure members are, in general, formed as a single piece and comprise a closing surface, which is the same as the can cross-section, and an annular contact region by which they can be sealed tightly to the inside lateral can surface around the entire can circumference. (For purposes of the invention all continuous (i.e., unbroken), closed surfaces will be referred to as annular regardless of whether their contour is circular, oval, or polygonal and regardless of whether they are formed with straight or curved lines.) The top closure member may preferably have a ring-pull for opening the can and/or reclosing elements, for example a snap lid. The bottom of the can is preferably sheet metal, even when the cylindrical, body portion (lateral surface) of the can consists of cardboard, and is hermetically sealed to the lateral surface in a conventional manner, e.g., by rolling.

[0014] An important advantage of a folding can according to the invention is that the insertion of a first closure member corresponds essentially to the insertion of the bottom of the can. If a foldable can cylinder is to be unfolded and provided with a first closure member just before filling, conventional apparatus for insertion of the bottom, e.g., a standard can closing machine, may be used for this purpose.

[0015] As noted above, containers having a cardboard lateral surface are frequently cylindrical with the lateral surface being formed as a wound cardboard tube. In order to produce a foldable can corresponding to such known boxes, the unfolded cylindrical lateral surface is provided with circular closure members. In the case of a foldable cylinder having just two folding edges, the cross-section can become increasingly flat with increasing distance from a closure member, depending on the method of unfolding. Therefore, in order to achieve a better approximation to the desired circular cross-section along the length of the can, more folding edges can be provided, the cylinder can be spread apart by a shaping means during unfolding, and/or the folding edges can be flattened out.

[0016] The final shape of the can also depends on the filling and on the second closure member. High resistance to deformation or crushing of the middle region of the can is achieved if the can cross-section is as circular as possible. Elliptical closure members, those which comprise circular segments or parts of ellipses, or polygonal closure members (particularly having an even number of sides that are of the same length, and preferably having rounded corners) may also be provided instead of circular closure members.

[0017] With a can according to the invention, it is also possible to provide unusual shapes in a simple manner. Specifically, the folding lines need not be flattened out, but, can be used as the edges of a polygonal can cylinder. Accordingly, the closure members or the bottom and the lid would also be polygonal, i.e., the number of folding edges and the number of corners of the closure members would correspond. In particular, tetragonal, preferably hexagonal or even octagonal to dodegonal cans can be provided.

[0018] Cardboard boxes with rounded edges and essentially rectangular cross-sections are also known. Such boxes have cylindrical body portions produced by winding cardboard webs around rectangular profiles. Because the “edges” are not folding edges as in the present invention, the lateral surface or body-forming cylinder cannot be flattened. The multi-edged cans according to the invention, in contrast have several flat, lateral surface sections which abut one another at the folding edges and which are not connected to one another by rounded transition regions. This provides distinct prism shapes which, particularly in the case of tetragonal or hexagonal cross-sections, can be tightly packed or arranged in honeycomb form.

[0019] Since the “closed” (i.e., continuous) or annular contact surface of each of the closure members presses tightly against the inside of the lateral surface, the can or the foldable cylinder has excellent stability and seal tightness. Closure members which have high compressive strength—e.g., plastic inserted or overlapping lid, which ensures can stability simply by being inserted into the cylinder—and closure members having high tensile strength—e.g., closure membranes which are firmly connected to the inside of the lateral surface or body member in a tensioned state—can both be used.

[0020] When filled, the can has a bottom, a lid, and, if desired, a closure or dispensing membrane. The closure membrane is expediently sealed to the cylinder by means of a double cone sealing apparatus, as described below.

[0021] The lid is in the form of an inserted or overlapping lid and is preferably made from plastic or, if desired, from cardboard or sheet metal. The bottom of the can is made from sheet metal, plastic, or cardboard and is connected to the lateral surface by folding, rolling, adhesive bonding, or sealing. The optionally provided membrane comprises a plastic film or paper sheet, but preferably an aluminum foil, and is hermetically sealed to the internal lateral can surface.

[0022] For the insertion and sealing of cardboard closure members, preferably by means of a hot-melt adhesive, it is possible to use press apparatuses which press against the abutting annular contact surfaces of the closure member and the cylinder from within and without (optionally from only one side) and supply heat to the contact surfaces during heat-sealing. Depending on the particular arrangement of the contact surfaces, the sealing surfaces lie either in the interior of the cylinder or along a separate sealing surface of the foldable cylinder.

[0023] In order to obtain essentially cylindrical connecting regions or contact surfaces connected to one another, a press apparatus having at least one radially adjustable press surface is provided. With such an apparatus, the press surface can be pressed against the contact surfaces after introduction of the apparatus. In the case of pressing from the inside of the cylinder, at least one press part (but preferably a plurality of press parts) having a convex press surface must be capable of being moved from a feed position in which it has a smaller press surface circumference to a pressing position in which it has a larger circumference. In the case of pressing from the outside of the cylinder, at least one press part (but preferably a plurality of press parts) having a concave press surface must be capable of being moved from a feed position in which it has a larger press surface circumference to a pressing position in which it has a smaller circumference. The parts which can be moved from the outside of the cylinder into their pressing positions may be dimensioned so that they form a step-free, closed (i.e., non-broken) circumferential line when they rest against one another.

[0024] Press apparatuses for polygonal can cross-sections are designed analogously to press apparatuses for cylindrical cans and preferably comprise radially movable press parts having flat press surfaces.

[0025] In order to impart greater stability to the foldable cylinder when it is in the unfolded state (i.e., when it is opened up), at least one bead, preferably transverse to the folding edges, may be provided in the lateral surface.

[0026] In a particularly preferred embodiment, the can comprises a closed cylinder which has at least one overlap-free connection between portions of the lateral surface-forming members, the edges of two corresponding lateral surface cylinder webs being adjacent to or abutting one another upon connection. The two lateral surface cylinder webs are then firmly connected to each other by a connecting element which overlaps the two webs. For this purpose, a strip-like connecting element having a sealing layer—preferably a hot-melt adhesive—is brought into contact with the cylinder webs to be connected and is preferably heat-sealed thereto. If desired, two connecting elements can be provided opposite to one another, i.e., connecting the lateral surface regions on both the inside and outside of the cylinder. For the production of a closed lateral surface, for example, the two side edges of a flat strip of material are connected to a connecting strip applied from the inside to the inner edge regions of the strip.

[0027] According to another aspect of the invention, it is possible to assemble a number—e.g., at least two, optionally four, preferably six, or even eight—of flat strips of can cylinder material with an appropriate number of connecting strips to form a tubular, double web of flat material. Sections can then be cut from the tubular, double web with a cutting apparatus to form the individual closed cylinders for packaging elements (cans) according to the invention. The flat material used comprises at least one layer, preferably of cardboard but optionally also of plastic.

[0028] The described connection of strips of flat material is simple and problem-free and makes it possible to provide a closed cylinder without overlapping regions. The connecting strips can be very thin if material of high tensile strength is used. If the thickness of the cylinder wall is to be uniform, it is expedient to use a compressible material—preferably cardboard—for the strips of flat cylinder material so that the thin connecting strips can be pressed into the flat, cylinder material. The inner surfaces of the cylinder webs, i.e., the strips of flat material, are preferably laminated with a thin aluminum and/or plastic layer. Accordingly, the sides of the connecting strips which face the cylinder webs are provided with a sealing layer and have an additional aluminum and/or plastic layer on the opposite side, i.e., the side which faces the interior of the cylinder, so that the interior of the cylinder is tightly sealed.

[0029] The overlap-free joints, or butt joints, are directly foldable. In order to obtain a foldable cylinder, it is merely necessary to choose the web widths of the individual cylinder webs and the number thereof such that at least two butt joints are the same distance apart in the circumferential direction so that the lateral wall can be collapsed flat. If just one cylinder “web” is used, with its side edges butt-joined to one another, the foldable cylinder can be provided by forming at least one fold line in the middle of the cylinder web so as to be diametrically opposite to the joined edges.

[0030] In the flat state, the volume of the foldable cylinder is essentially just the material volume. In other words, essentially no empty volume is transported from the cylinder factory to the filling site. The foldable cylinder is preferably unfolded immediately before filling and is provided with at least one closure member at a first end region thereof. If the closure member is firmly connected to a free cylinder edge along the edge, the cylinder is given the desired shape or cross-section at least in the region of the closure member. After filling, another closure member is mounted at a second, opposite region of the cylinder so that the can is closed and the cylinder is given the desired shape in the second end region as well.

DESCRIPTION OF THE DRAWINGS

[0031] The invention will be described in detail with reference to the following drawings in which:

[0032]FIG. 1 is a perspective view, partially broken away, showing an embodiment of a folding can according to the invention;

[0033]FIG. 2 is an end view of a foldable cylinder, in the flattened state, used to construct the can shown in FIG. 1;

[0034]FIG. 3 is a cross section through a cylinder, in the unfolded state, used to construct another embodiment of a can according to the invention;

[0035]FIG. 4 is a perspective view, partially broken away, showing another embodiment of a can according to the invention;

[0036]FIG. 5 is an end view of a foldable cylinder, in the flattened state, used to construct the can shown in FIG. 4;

[0037]FIG. 6A is a perspective view, partially broken away, of another embodiment of a can according to the invention;

[0038]FIG. 6B is an end view of a foldable cylinder, in the flattened state, used to construct the can shown in FIG. 6A;

[0039]FIG. 7A is a perspective view, partially broken away, of another embodiment of a can according to the invention;

[0040]FIG. 7B is an end view of a foldable cylinder, in the flattened state, used to construct the can shown in FIG. 7A;

[0041]FIG. 8A is a partial section view, along the lines 8A-8A, through the wall of the cylinder of the embodiment shown in FIG. 7A;

[0042]FIG. 8B is a partial section view, along the lines 8B-8B, through the wall of the cylinder of the embodiment shown in FIG. 7A;

[0043]FIG. 9 is an end view of a foldable cylinder, in the opened or unfolded state, used in the construction of another embodiment of a can according to the invention;

[0044]FIG. 10 is a perspective view showing the construction of a foldable cylinder for a can according to another embodiment of the invention;

[0045]FIG. 10A is a section view, along the lines 10A-10A in FIG. 10, showing the line of abutment of a single cylinder web used to construct the foldable cylinder shown in FIG. 10;

[0046]FIG. 11 shows a partial assembly line used to produce foldable cylinders for use in constructing cans according to the invention;

[0047]FIGS. 12 and 13 are perspective views showing two additional embodiments of folding cans according to the invention; and

[0048]FIGS. 14A and 14B are schematic views demonstrating the sealing of a can constructed according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0049]FIG. 1 shows a first embodiment of a can 1 according to the invention. The can is formed from a foldable cylinder 2, which defines the lateral surface of the can, that is divided by two folding edges 3 into two lateral webs or part-surfaces 2 a, 2 b of equal size. The foldable cylinder 2 is formed from a cardboard sheet by forming a connection 2′ by overlapping the two lateral end regions 2 a′ and 2 b′ of the cardboard sheet, particularly in the region of a folding edge 3.

[0050] Before the can 1 is filled, a circular dispensing membrane 4, for example, having outlet orifices 5 that are covered by a removable closure element 6 (e.g., a flap) is disposed on the first end region 10 of the unfolded foldable cylinder 2. The dispensing membrane 4 is beneficially sealed to the foldable cylinder 2 by introducing a pressing or shaping means (not shown) into the interior of the first end region 10 from the second end region 20, pressing the annular connecting region 4 a of the dispensing membrane 4 against the outer surface of the foldable cylinder 2 from the outside, and securing it to the cylinder by heat sealing. In the embodiment shown in FIG. 1, the dispensing membrane 4 forms an end surface of the can 1; optionally, an overlapping lid 7 can be mounted on the end 10 of the can with the lid fitting tightly against the dispensing membrane 4 when it is closed.

[0051] After the can is filled, a can bottom 8 is inserted in and attached to the end 20. In the embodiment shown, it is in the form of a cardboard bottom. A bottom-forming member 8 a is inserted into the interior of the can cylinder 2, and two connecting members 9 are connected to the cylinder end 20. In order to attach the two connecting members 9 securely to the cylinder 2, the pressing apparatus used to attach them (not shown) must have at least two pressing surfaces, one of which presses from the inside of the cylinder and one of which presses from the outside of the cylinder.

[0052]FIG. 2 shows the foldable cylinder 2 used in the embodiment of FIG. 1 (i.e., one having two folding edges 3) in the collapsed or flattened state. As indicated at the left end of the figure, the overlap joint 2′ may be formed by pressing the end regions 2 a′ and 2 b′ together in such a way that the wall thickness in the overlap region is only insignificantly increased, if not decreased.

[0053]FIG. 3 shows a cross-section through the cylinder 102 of another embodiment of a can that is produced, for example, by winding. The cylinder 102 has six equally spaced folding edges 103, which are preferably formed as flutes. The folding edges 103 may be formed in any other desired manner, e.g., as notches on the inside and/or outside surfaces of the cylinder 102. Because the cylinder has more than two folding edges 103, and hence more than two webs or cylinder panels 102 a- 102 f, the can cylinder is less likely to be flattened between the bottom and the lid and therefore tends to retain its shape better than a can with only two folding edges does.

[0054]FIG. 4 shows a hexagonal can 200 whose six edges are formed as folding edges 203. Before the can 200 is filled, a hexagonal closure membrane 214 is fastened to the first, upper can end 210 by means of an annular connecting region 214 a of the membrane such that the closure membrane 214 extends into the interior of the can cylinder 202 and such that a hexagonal lid 224 can be inserted into the can cylinder 202, from the outside of the cylinder, against the closure membrane 214 from the first end 210. In order to be able to remove the inserted lid 224, the lid preferably has an inwardly projecting gripping edge 224 a. When the connecting region 214 a is pressed against the inside surface of the foldable cylinder 202, hexagonally arranged pressing means (not shown) must be provided in the case of the hexagonal can. After the can is filled, a hexagonal bottom 208 preferably is attached at the bottom of the can in the same manner as in the embodiment shown in FIG. 1. The pressing surfaces (not shown) required for this purpose must have a hexagonal arrangement, also.

[0055] Analogously to FIG. 2, FIG. 5 shows the foldable cylinder 202 of the embodiment shown in FIG. 4 in the collapsed or flattened state.

[0056] It will be appreciated that an installation (not shown) for filling cans constructed according to the invention comprises, in addition to means for filling the can through a second orifice and means for closing the second orifice after the can is filled, means for unfolding a flattened foldable cylinder 2, 102, or 202 and for inserting a closure member 4, 214, and/or 224 in the first can orifice formed by the foldable cylinder before the can is filled. For example, manipulators such as suction elements or rams and/or spreadable elements insertable into the cylinder are used for unfolding. Any of various known connecting apparatuses can be used to seal the closure member to the cylinder.

[0057]FIG. 6A shows another embodiment 300 of a can according to the invention. The embodiment 300 is similar to the embodiment 200 of FIG. 4 in that it has a hexagonal foldable cylinder 302 which is divided into six partial-lateral-surface members or cylinder webs 302 a-302 f of equal size, by six folding edges 303. Before the can 300 is filled, a hexagonal closure membrane 314 having an annular connecting portion 314 a is sealed to the first can end 310 such that the closure membrane 314 is located in the interior of the can. A hexagonal lid 324 can be inserted into the can cylinder 302 from the outside so as to bear against the closure membrane 314 and seal it against the inside surface of the first can end 310. In order to be able to remove the lid 324, the lid preferably has an inwardly projecting gripping edge 324 a. A generally annular shaping element (not shown) optionally can be connected to the cylinder 302—preferably in the end region 310 that is closable with the lid 324—in order to ensure the desired cross-section. The annular connecting region 314 a of the closure membrane 314 is sealed against the inside cylinder surface in the same fashion as in the case of the embodiment shown in FIG. 4.

[0058] As shown in FIGS. 6 and 6B, the cylinder webs 302 a-302 f are connected to each other by connecting strips 330 in the interior of the can. Each of the connecting strips 330 joins two abutting cylinder webs 302 a-302 f, preferably with half a connecting strip overlapping each of the webs. The connecting strips 330 preferably are connected to the cylinder webs by heat-sealing. The cylinder webs and the connecting strips 330 extend parallel to the cylinder axis. The cylinder can be folded flat (before any closure members are attached), and the lines of abutment between cylinder webs can be used as the folding edges 303.

[0059]FIGS. 7A and 7B show an embodiment 400 of a can 400 whose cylinder 402 consists of a single cylinder web. The end regions of the cylinder web, which are parallel to the axis of the can, abut each other along a connecting line and are secured to one another by means of a connecting strip 430. In order to be able to flatten the cylinder, a folding edge 403 (in addition to the connecting line, which functions as a folding edge) is provided in the middle of the cylinder web, e.g., by flutes, scores, notches or embossings. A plurality of folding edges, e.g., 4, 6, 8, 12, or more, can be provided such that the cross-section of the finished can is approximately circular. In the extreme case, a single connecting strip 430 may be sufficient.

[0060] Before filling, the cylinder is unfolded and a circular membrane—e.g., a dispensing membrane 404 having outlet orifices 405 that are covered by a removable closure element 406, e.g., a flap—is sealed to the first end region 410 of the unfolded foldable cylinder 402. When the dispensing membrane 404 is sealed to the foldable cylinder 402, a pressing or shaping means (not shown) may be introduced into the interior of the first end region 410 from the second end region 420; an annular connecting portion 404 a of the dispensing membrane 404 is pressed, from the outside of the cylinder, against the foldable cylinder 402 and is sealed to it by heat-sealing. In the embodiment shown, the dispensing membrane 404 forms an end surface of the can 400 over which an overlapping lid 407 can be mounted, resting tightly against the dispensing membrane 404 when in the closed state.

[0061] After the can 400 has been filled, a bottom 408 is inserted. In the embodiment shown, the bottom is cardboard. The bottom surface 408 a is located in the interior of the cylinder, and two connecting surfaces 409 are connected to the cylinder end. In order to secure the two connecting surfaces 409 to the cylinder 402, the press apparatus used (not shown) preferably has at least two press surfaces, in which case one presses from the inside of the cylinder and one presses from the outside of the cylinder.

[0062] To ensure that the side surfaces of the cylinder webs (i.e., the abutting edges) are not accessible from the outside of the can, e.g., through a gap, a labeling strip 431 is secured around the can such that it overlays the outer surface of the cylinder 402, as shown in detail in FIG. 8A. Where the lateral (i.e., edges) surfaces of the cylinder web are joined together, the labelling strip 431 is gathered slightly to provide “free” regions 431 a, which permit the cylinder to be folded. In order to provide a step-free inner surface of the cylinder, the connecting strip 130 may be pressed into the material of the cylinder web during heat-sealing. Furthermore, the cylinder web preferably is coated with a tight, moisture-resistant inner layer 432.

[0063]FIG. 8B shows a similar section through the butt joint formed by the two side regions of the cylinder web, but in the region of the attached bottom whose edge portions 409 overlap the lower edge of the cylinder 402. By sealing the edge portions 409 against one another with the labeling strip 431 (in particular, the free region 431 a) disposed in between, the labeling strip is tightly compressed. The bottom 408 a can thus be connected extremely tightly and securely to the cylinder 402.

[0064]FIG. 9 shows an unfolded cylinder 502 that is assembled from four cylinder webs 502 a-502 d and four connecting strips 530. The cross-sectional shape consists of two semicircular regions on either side of a rectangular region. Of course, any desired cross sectional shapes are possible.

[0065]FIG. 10 illustrates schematically the provision of a cylinder tube 602 having a rectangular cross section. The cylinder tube 602 is produced from a single cylinder web in which four folding lines 603 are embossed at an embossing station (not shown). The cylinder web is folded along the folding lines 603 to produce the illustrated cylinder tube 602, with lateral edges of the cylinder web abutting one another along connecting line 600. The folding edges 603 of the cylinder tube 602 are formed by folding along the folding lines. The connecting line 600 lies between two folding edges 603. In order to seal the abutting edges of the cylinder web firmly together, a connecting strip 630 is applied (preferably heat-sealed) by means of applicator rolls 610, both on the inside and the outside of the cylinder, along the connecting line 600. This embodiment demonstrates that the connection of the cylinder web borders can be effected independently of the formation of the folding edges 603; this is advantageous particularly when the connection should guarantee the greatest possible stability.

[0066]FIG. 10A shows a section through the connection of the cylinder web edges, as shown in FIG. 10A. High stability is ensured by the connecting strips 630 being arranged on both sides of, and firmly connected to, the edge regions of the cylinder web.

[0067]FIG. 11 shows a partial assembly line for the production of packaging elements (cans) having foldable cylinders that are closed (circumferentially speaking) without overlap and which are made from several cylinder webs. At least one unwind apparatus (not shown) is provided for feeding a supply of flat material 150 from which the cylinders are formed. In the embodiment shown in FIG. 11, the flat material 150 is unwound from a large supply roll 151 and is cut into four webs 150 a-150 d by a cutting apparatus having five knives 152. Alternatively, the webs 150 a-150 d could be fed in from separate, smaller rolls. Thereafter, four connecting strips 130 are fed from a feed apparatus (not shown) and applied to the adjacent edge surfaces of webs to be connected to one another. It will be appreciated that one of the connecting strips 130 (the frontmost one in FIG. 11) is initially applied to only a single web, e.g., 150 d.

[0068] A first sealing unit 153 securely fastens the connecting strips 130 to the cylinder webs, e.g., by heat-sealing. Subsequently, the laterally projecting connecting strip portion 130 a and the laterally opposite webs are folded inward, as indicated by the curved arrows in FIG. 11. Then, at a second sealing unit 154, these are connected to one another to provide a flattened tube of web material. At a subsequent cutting apparatus 155, sections of the tube are cut off to form the closed cylinders for packaging elements e.g., cans. The installation is of simple design and permits trouble-free operation, even at high feed rates.

[0069] After the cutting apparatus 155, an apparatus (not shown) may be provided to apply one or more labeling strips 131 in an annular manner around the flattened cylinder, the labeling strips 131 being fastened to the outer surfaces of the cylinder with free regions (like those shown in FIG. 8A) being provided to permit folding of the cylinder. Alternatively, the labeling strips can be bonded adhesively to the cylinder in a manner known per se after unfolding of the cylinder or even after filling of the can, in which case it is possible to forego the free regions for folding, and higher stability and better visual effect are achieved.

[0070]FIG. 12 shows a can 701 having a hexagonal bottom 708, a circular dispensing membrane 704, and a foldable cylinder 702 which is assembled from six cylinder webs 702 a-702 f connected to one another. The cylinder cross-section changes from hexagonal at the bottom of the cylinder to circular at the top of the cylinder. A circular lid (not shown) which turns in any desired direction can be mounted on the circular upper end region of the can 701. The angular lower end region the can 701 from rolling if the can is knocked over.

[0071]FIG. 13 shows another embodiment of a can 801 having a circular bottom 808 and a foldable cylinder 802 which is formed from a closed sheet having six folding lines 803. Of course, it is possible to provide only two folding lines 803 and/or to assemble the cylinder from individual cylinder webs. At the upper end, the can is not provided with a closure member, but rather is closed by a linear seal connection 810. To produce the linear seal connection 810, the upper end region of the cylinder 802 is pressed together. The inner surfaces of the cylinder end region which are thereby pressed against one another are then sealed to one another, e.g. by heat-sealing. An emptying orifice can be provided, for example, by pulling off a lateral end region or a tear-off corner 811 along a predetermined tear line.

[0072] In the production of closed (i.e., continuous) can cylinders, it is advantageous if a closed cylinder tube is first produced using at least one cylinder web, with cylinder sections of the desired length being cut from the tube only thereafter. This makes it possible to connect the cylinder web edges in a continuous procedure. Otherwise, if individual cylinder web sheets of the desired final length are first cut, all cylinder web sheets must subsequently be fed individually to a connecting station and correctly connected.

[0073] It has been found that, even when a single cylinder web is glued along an overlap region, production installations like those shown in FIG. 11 are preferable. In such situation, longitudinal splitting of the cylinder web and application of connecting strips are foregone. The cylinder web needs to be folded only twice before the adjacent cylinder regions are connected or glued to one another.

[0074] Finally, FIGS. 14A and 14B illustrate the process for sealing a (the upper) can opening by sealing in a closure membrane 214 (see FIG. 1, for example). A thermoformed membrane film 214 which has a collar 213 that projects over the upper edge of the can cylinder 202, rests with the collar on the edge of the cylinder. A heated, outer sealing ring 180 having a slightly beveled (e.g., 2°) inner surface 180′ moves from an upper, waiting position (FIG. 14A) to a lower, sealing position (FIG. 14B) in which it seals the membrane collar 213 onto the outside of the cylinder and/or the axial part 214′ of the membrane film 214 onto the inside surface of the cylinder. The inner heat-sealing die 190 has a complementarily slightly beveled (e.g., 2°) outer surface 190′ against which the sealing ring 180 presses when in the sealing position.

[0075] It will be apparent that the invention is not restricted to the embodiments shown. Any desired closure member with any desired connection to the can cylinder can be used. Moreover, by using suitable hot-melt adhesives, it is possible, in certain circumstances, to connect together the abutting cylinder web edges without using connecting strips. Other embodiments are deemed to be within the scope of the following claims. 

1. A can comprising a circumferentially continuous, unfolded foldable cylinder having a longitudinal axis, and at least one closure member hermetically sealed to said foldable cylinder along an annular contact surface, wherein said foldable cylinder has at least two longitudinally extending folding edges formed and circumferentially located such that said foldable cylinder can be flattened, then unfolded for hermetic sealing of said closure member to said foldable cylinder.
 2. The can of claim 1 , wherein said at least one closure member comprises a bottom of said can and is formed from a material selected from the group consisting of plastic, cardboard, and metal.
 3. The can of claim 1 , wherein said at least one closure member comprises a bottom of said can and said bottom is in the form resulting from having been attached to said cylinder by at least one of the methods in the group consisting of rolling, adhesive bonding, and heat-sealing.
 4. The can of claim 1 , wherein said closure member comprises a dispensing membrane.
 5. The can of claim 1 , wherein said can comprises a polygonal closure member at an upper end of said cylinder and a polygonal closure member at a lower end of cylinder and folding edges extend along said foldable cylinder from corners of the upper closure member to corners of the lower closure member.
 6. The can of claim 1 , wherein said foldable cylinder comprises a single cardboard cylinder web, said cylinder web having opposite lateral edges which are overlapped and sealed to each other by one or more of the methods in the group consisting of adhesive bonding and heat-sealing.
 7. The can of claim 1 , wherein said foldable cylinder comprises cardboard strips obliquely wound with respect to said longitudinal axis.
 8. The can of claim 1 , wherein said foldable cylinder comprises at least one overlap-free region extending along the length of said cylinder and parallel to said longitudinal axis, said at least one overlap-free region comprising edges of one or more cylinder webs abutting each other in face-to-face relation along a connection line and sealed together along said connection line.
 9. The can of claim 8 , wherein said connection line is disposed between two folding edges.
 10. The can of claim 8 , wherein said edges are sealed together by means of one or more strip-form connecting elements which extend along the length of each said connection line and which overlap the abutting edges.
 11. The can of claim 10 , wherein said strip-form connecting elements are disposed along at least one of the surfaces in the group consisting of inner-facing surfaces and outer-facing surfaces of said one or more cylinder webs.
 12. The can of claim 1 , wherein said foldable cylinder comprises at least six folding edges.
 13. The can of claim 1 , wherein said can comprises a closure member at an upper end of said cylinder and a closure member at a lower end of said cylinder, said upper and lower closure members being differently shaped whereby the cross-sectional profile of said can changes from the bottom end of said cylinder to the upper end of said cylinder.
 14. The can of claim 1 , wherein said can has a single closure member at a lower end thereof and an opposite, upper end of said can is sealed by means of said foldable cylinder being flattened and sealed shut.
 15. The can of claim 8 , wherein said cylinder webs are formed from cardboard; inner-facing surfaces of said cylinder webs are laminated with a thin layer of aluminum, plastic, or aluminum and plastic; said strip-form connecting elements are glued or heat-sealed to said cylinder webs on inner-facing surfaces thereof; and said strip-form connecting elements comprise aluminum, plastic, or aluminum and plastic; whereby said connection lines are hermetically sealed.
 16. The can of claim 1 , further comprising a labeling strip encircling said foldable cylinder and fastened to the outer-facing surface of said cylinder.
 17. The can of claim 16 , wherein said labeling strip comprises paper.
 18. The can of claim 8 , further comprising a labeling strip encircling said foldable cylinder and fastened to one or more of said cylinder webs, said labeling strip having free regions which facilitate folding of said foldable cylinder.
 19. A production line for manufacturing foldable, cylindrical packaging elements, said production line comprising means for providing a continuous supply of flat, sheet-form material from which said foldable, cylindrical packaging elements are constructed; means for forming said flat, sheet-form material into an annularly connected, tubular cylinder, including means for connecting portions of said flat, sheet-form material to each other in sealed, abutting, or overlapping fashion; and means for cutting said tubular cylinder transverse to a longitudinal axis thereof to provide individual foldable, cylindrical packaging elements.
 20. The production line of claim 19 , wherein said means for connecting comprises a feed apparatus for providing one or more continuous, strip-form connecting members, means for applying said one or more strip-form connecting members to said portions of said flat, sheet-form material, and means for heat-sealing said one or more strip-form connecting members to said portions of said flat, sheet-form material.
 21. The production line of claim 19 , wherein said means for providing comprises a cutting apparatus configured to cut a first, longitudinally continuous sheet of said sheet-form material into a plurality of narrower, longitudinally continuous cylinder webs.
 22. The production line of claim 19 , wherein said means for providing is configured to provide said supply of flat, sheet-form material in the form of a plurality of longitudinally continuous cylinder webs.
 23. The production line of claim 19 , further comprising means for applying one or more labeling strips in annular fashion to outer surfaces of said foldable, cylindrical packaging elements.
 24. A packaging apparatus for closing a can as set forth in claim 1 with a membrane by means of heat-sealing, said packaging apparatus comprising an inner, heat-sealing die and an outer, sealing ring, wherein an outer surface of the heat-sealing die and an inner surface of the sealing ring are beveled slightly in mating fashion.
 25. The apparatus of claim 24 , wherein said outer and inner surfaces are each beveled by approximately two degrees. 